The present invention relates to energy saving. More specifically, the present invention relates to an energy-saving operation of a storage device which has a movable read/write head.
There is little doubt today as to the need for energy saving. Electrical energy conservation is an important element of energy policy, reducing energy consumption and demand, in the attempt to balance the increasing energy demand of the world's growing population with the decline of energy resources and soaring energy costs. Reducing power consumption in computer systems has undoubtedly become an important issue.
A hard disk drive device typically includes one or more flat disks called platters (42, see FIG. 4), which are coated with a layer of magnetic material, onto which data is recorded or read by a head (hereinafter—read/write head, 46, see FIG. 4) held by an actuator arm (48, FIG. 4) and actuated by an actuator (43, FIG. 4) to move across the platter (indicated by arrows in FIG. 4). The platter is coupled to and rotated by a spindle (44, FIG. 4). By incorporating rotation of the platter with motion of the head over the platter it is possible to bring the head over a desired data block and write onto it or read it.
Hard disks are typically provided with an acoustic management capability, which facilitates control over the level of noise generated by the hard disk drive. In hard disk drives with acoustic management the seek speed of the read/write head (i.e. the speed at which it is moved to reach its target position) is controlled. In many such hard disk drives several seek speeds are available (also refereed to as “acoustic modes”).
Attempts were made to reduce the acoustic noise of disk storage. For example, it was proposed in the past to actively control the seek speed so that the head arrives at its destination only just in time to read the desired data block, rather than arriving as quickly as possible and then having to wait for the data block to come around (phenomenon known as the “rotational latency”).
Another way of reducing energy consumption was to reduce the spin speed of storage disks to reduce energy consumption and generate less waste heat.